Co-sleeping is recognized as an important physical contact that allows an infant to psychologically grow. The co-sleeping that allows such an effect is typically conducted by putting a baby in the bed of a co-sleeper or neighbor to a co-sleeper. Further, the co-sleeping may be conducted by placing a bed of the co-sleeper neighbor to a baby-bed so that the co-sleeper tips the bar that surrounds the baby bed neighbor to the bed of the co-sleeper so as to lean out of the bed to comfort the baby. Further, a co-sleeping method may be conducted by placing a so-called co-sleeping bed that is surrounded by three sides except the side of the foot on the bed so that adults let the baby sleep inside the bed for adults.
For example, Japanese Utility model Publication No. 3126368 published Apr. 10, 2006, incorporated herein in its entirety, discloses a cushion used at the abdomen or back of the mother for breast-feeding during co-sleeping for the baby, and Japanese Utility model Publication No. 3079794 published Jun. 13, 2001, incorporated herein in its entirety, discloses a mat used for arm pillow during co-sleeping with a baby. The side of the mat for a head of the baby leans upward while a concave portion is provided in which an arm is placed for arm pillow.